It is common for equipment modules to be designed and operated according to different maintenance approaches. For example, it is conventional for an equipment module, which may be an individual component, a component within a system, or a system of components, to be designed and operated in accordance with one of an “operate-to-failure maintenance approach” or a “scheduled maintenance approach.”
The scheduled maintenance approach refers to a process of replacing or servicing an equipment module at a scheduled interval, such as an interval based on hours of use. The goal of the scheduled maintenance approach is to schedule maintenance intervals so that equipment modules are serviced or replaced before they fail, so that failure is avoided. If maintenance intervals are scheduled too frequently, the benefits resulting from the performed maintenance may be offset by excessive maintenance expenses. If maintenance intervals are not scheduled frequent enough, the benefits resulting from the performed maintenance may be offset by excessive failures of equipment modules.
The operate-to-failure maintenance approach refers to operating an equipment module until failure, without using the scheduled maintenance approach or the prognostic maintenance approach. The equipment module is replaced after it fails. Depending upon the type of equipment module, the operate-to-failure maintenance approach may include more than just the cost of replacing the failed equipment module because the failure of one equipment module may cause collateral damage also. For example, if a bearing of an engine is allowed to totally fail, then the lack of the bearing may cause the housing or shaft of the engine to also be damaged or fail.
In addition to the scheduled maintenance approach and the operate-to-failure maintenance approach, it is also advantageous to consider and evaluate a “prognostic maintenance approach” for an equipment module. The prognostic maintenance approach refers to a process of prognosticating (that is, using present indications as a guide) to predict a failure in advance. The prognostic maintenance approach typically requires monitoring characteristics of the equipment module that can provide an indication of an impending problem with the equipment module. In some cases, the equipment module must be designed in a manner that facilitates the monitoring of the characteristic(s) that are of interest. The goal of the prognostic maintenance approach may be to replace an equipment module just prior to a predicted failure of that equipment module. Alternatively, the goal may be to replace or service an equipment module just prior to the equipment module being degraded to a point at which the cost of the replacement or servicing becomes excessive. If too much effort is put into a prognostic maintenance approach, the benefits resulting therefrom may be offset or outweighed by excessive expenses associated with the prognosticating. If insufficient efforts are put into a prognostic maintenance approach, then the benefits resulting therefrom may be offset or outweighed by excessive failures of equipment modules.
The general concepts of the operate-to-failure maintenance approach, the prognostic maintenance approach, and the scheduled maintenance approach are well known, but it can be difficult to select between these maintenance approaches when designing or operating an equipment module. In addition, although there are systems that quantify the cost associated with these maintenance approaches by taking certain basic factors regarding the equipment module into consideration, these systems perform the quantification for each equipment module separately, such that the quantification must be performed numerous times for each equipment module. Furthermore, conventional quantification systems often require only rough estimates of inputs regarding the equipment module and do not take into account any type of economic factors, such that the quantification of cost of the equipment module with one of the maintenance approaches provides a rough amount that can be analyzed relative to the quantifications of other equipment modules and/or other maintenance approaches, but the costs are generally not very accurate. As a result, designers and operators of equipment modules often do not have accurate quantifications to optimally select from the operate-to-failure maintenance approach, the prognostic maintenance approach, the scheduled maintenance approach or other approaches, such that it is common for the design and operation of equipment modules to be less than optimal.